Liquid crystal display

ABSTRACT

A liquid crystal display includes a first insulating substrate, pixel electrodes disposed on the first insulating substrate and divided into a plurality of domains, each domain including micro-concave stripes and micro-convex stripes arranged in a specific direction, a second insulating substrate facing the first insulating substrate, a common electrode, which is not patterned, disposed on the second insulating substrate, and a liquid crystal layer interposed between the first and second insulating substrates and including liquid crystal molecules. The liquid crystal molecules are aligned perpendicular to the first and second insulating substrates when an electric field is not applied to the liquid crystal layer, and the liquid crystal molecules are inclined in an extension direction of the micro-concave stripes and the micro-convex stripes when an electric field is applied to the liquid crystal layer.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority from and the benefit of Korean PatentApplication No. 10-2007-0127065, filed on Dec. 7, 2007, which is herebyincorporated by reference for all purposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a display and more particularly, to aliquid crystal display.

2. Discussion of the Background

Liquid crystal displays are widely used flat panel displays. A liquidcrystal display includes two display panels on which field-generatingelectrodes, such as pixel electrodes and a common electrode, aredisposed, and a liquid crystal layer that is disposed between thepanels. In the liquid crystal display, voltages are applied to thefield-generating electrodes to generate an electric field in the liquidcrystal layer. The alignment of liquid crystal molecules of the liquidcrystal layer is determined by the electric field, and the polarizationof incident light is controlled, so that images are displayed.

Among liquid crystal displays, vertical alignment (VA) mode liquidcrystal displays have been focused on recently because they have highcontrast ratios and wide viewing angles, in which major axes of liquidcrystal molecules are perpendicular to the upper and lower displaypanels when no electric field is applied. In order to achieve a wideviewing angle in such a liquid crystal display, gaps may be formed in afield-generating electrode, or protrusions may be formed above or belowthe field-generating electrode.

Patterned Vertical Alignment (PVA) mode liquid crystal displays andpatternless VA mode liquid crystal displays have gaps. In the PVA modeliquid crystal display, gaps are formed on both upper and lowersubstrates. In the patternless VA mode liquid crystal display,micro-patterns are formed on a lower substrate, but not on an uppersubstrate.

In the case of a liquid crystal display having a large area, since thesize of a pixel is increased, it may be difficult to effectively controlthe movement of the liquid crystal molecules and therefore thedirectionality of liquid crystal molecules may be unstable. As a result,the response speed may be decreased.

SUMMARY OF THE INVENTION

The present invention provides a liquid crystal display that maysimultaneously improve response speed and luminance.

Additional features of the invention will be set forth in thedescription which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention.

The present invention discloses a liquid crystal display including afirst insulating substrate, pixel electrodes disposed on the firstinsulating substrate and divided into a plurality of domains, eachdomain including micro-concave stripes and micro-convex stripes arrangedin a specific direction, a second insulating substrate facing the firstinsulating substrate, a common electrode, which is not patterned,disposed on the second insulating substrate, and a liquid crystal layerdisposed between the first and second insulating substrates andincluding liquid crystal molecules. The liquid crystal molecules arealigned perpendicular to the first and second insulating substrates whenan electric field is not applied to the liquid crystal layer, and theliquid crystal molecules are inclined in an extension direction of themicro-concave stripes and the micro-convex stripes when an electricfield is applied to the liquid crystal layer.

The present invention also discloses a liquid crystal display includinga first insulating substrate, pixel electrodes disposed on the firstinsulating substrate, having a bent structure, and includingmicro-concave stripes and micro-convex stripes that extend along edgesof the pixel electrode to be orthogonal to the edges of the pixelelectrode, a second insulating substrate facing the first insulatingsubstrate, a common electrode disposed on the second insulatingsubstrate and including a domain-dividing portion, and a liquid crystallayer disposed between the first and second insulating substrates andincluding liquid crystal molecules. The liquid crystal molecules arealigned perpendicular to the first and second insulating substrates whenan electric field is not applied to the liquid crystal layer, and theliquid crystal molecules are inclined in an extension direction of themicro-concave stripes and the micro-convex stripes when an electricfield is applied to the liquid crystal layer.

The present invention also discloses a liquid crystal display includinga first insulating substrate, pixel electrodes disposed on the firstinsulating substrate, having a bent structure, and includingmicro-concave stripes and micro-convex stripes that extend along edgesof the pixel electrode to be orthogonal to the edges of the pixelelectrode, control electrodes overlapping with cut-out portions in thepixel electrodes, the control electrodes receiving a voltage higher thanthat applied to the pixel electrodes, a second insulating substratefacing the first insulating substrate, a common electrode, which is notpatterned, disposed on the second insulating substrate, and a liquidcrystal layer disposed between the first and second insulatingsubstrates and including liquid crystal molecules. The liquid crystalmolecules are aligned perpendicular to the first and second insulatingsubstrates when an electric field is not applied to the liquid crystallayer, and the liquid crystal molecules are inclined in an extensiondirection of the micro-concave stripes and the micro-convex stripes whenan electric field is applied to the liquid crystal layer.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention, andtogether with the description serve to explain the principles of theinvention.

FIG. 1 is a layout of a liquid crystal display according to a firstexemplary embodiment of the present invention.

FIG. 2 is a cross-sectional view of the liquid crystal display takenalong line II-II′ of FIG. 1.

FIG. 3 is a partially sectioned perspective view of the liquid crystaldisplay shown in FIG. 1.

FIG. 4A, FIG. 4B, and FIG. 4C are cross-sectional views showingprocesses of a method of manufacturing the liquid crystal displayaccording to the first exemplary embodiment of the present invention.

FIG. 5A is a layout of a liquid crystal display according to a secondexemplary embodiment of the present invention.

FIG. 5B is a cross-sectional view of the liquid crystal display takenalong line Vb-Vb′ of FIG. 5A.

FIG. 6A is a layout of a liquid crystal display according to a thirdexemplary embodiment of the present invention.

FIG. 6B is a cross-sectional view of the liquid crystal display takenalong line VIb-VIb′ of FIG. 6A.

FIG. 7 is a layout of a lower display panel of a liquid crystal displayaccording to a fourth exemplary embodiment of the present invention.

FIG. 8 is a cross-sectional view of the lower display panel taken alongline VIII-VIII′ of FIG. 7.

FIG. 9 is a cross-sectional view of the lower display panel taken alongline IX-IX′ of FIG. 7.

FIG. 10 is a layout of an upper display panel included in the liquidcrystal display according to the fourth exemplary embodiment of thepresent invention.

FIG. 11 is a layout of the liquid crystal display that includes thelower display panel of FIG. 7 and the upper display panel of FIG. 10.

FIG. 12 is a layout of a liquid crystal display according to a fifthexemplary embodiment of the present invention.

FIG. 13 is a cross-sectional view of the liquid crystal display takenalong line XIII-XIII′ of FIG. 12.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

The invention is described more fully hereinafter with reference to theaccompanying drawings, in which embodiments of the invention are shown.This invention may, however, be embodied in many different forms andshould not be construed as limited to the embodiments set forth herein.Rather, these embodiments are provided so that this disclosure isthorough, and will fully convey the scope of the invention to thoseskilled in the art. In the drawings, the size and relative sizes oflayers and regions may be exaggerated for clarity. Like referencenumerals in the drawings denote like elements

It will be understood that when an element or layer is referred to asbeing “on”, “connected to,” or “coupled to” another element or layer, itcan be directly on, connected, or coupled to the other element or layeror intervening elements or layers may be present. In contrast, when anelement is referred to as being “directly on”, “directly connected to,”or “directly coupled to” another element or layer, there are nointervening elements or layers present. As used herein, the term“and/or” includes any and all combinations of one or more of theassociated listed items.

Spatially relative terms, such as “beneath”, “below”, “lower”, “above”,“upper”, and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures.

Embodiments described herein will be described referring to plan viewsand/or cross-sectional views by way of ideal schematic views of theinvention. Accordingly, the exemplary views may be modified depending onmanufacturing technologies and/or tolerances. Therefore, the embodimentsof the invention are not limited to those shown in the views, butinclude modifications in configuration formed on the basis ofmanufacturing processes. Therefore, regions exemplified in figures haveschematic properties and shapes of regions shown in figures exemplifyspecific shapes of regions of elements and not limit aspects of theinvention.

A liquid crystal display according to a first exemplary embodiment ofthe present invention will be described below with reference to FIG. 1,FIG. 2, and FIG. 3. FIG. 1 is a layout of a liquid crystal displayaccording to a first exemplary embodiment of the present invention. FIG.2 is a cross-sectional view of the liquid crystal display taken alongline II-II′ of FIG. 1. FIG. 3 is a partially sectioned perspective viewof the liquid crystal display shown in FIG. 1.

Referring to FIG. 1 and FIG. 2, the liquid crystal display according tothe first exemplary embodiment of the present invention includes a lowerdisplay panel 150, an upper display panel 160, and a liquid crystallayer 170. The lower display panel 150 includes thin film transistorsthat are connected to gate lines 22 and data lines 62 and that applydata voltages to pixel electrodes 82. The upper display panel 160 facesthe lower display panel 150, and includes a common electrode 120. Theliquid crystal layer 170 is interposed between the lower display panel150 and the upper display panel 160. According to the present exemplaryembodiment, color filters 92 and a thin film transistor array aredisposed on the lower display panel 150. The present exemplaryembodiment is described by using an Array On Color filter (AOC)structure where the thin film transistor array is disposed on the colorfilters 92. However, the present invention is not limited thereto. Thatis, exemplary embodiments of the present invention also may employ Colorfilter On Array (COA) structure where color filters and a thin filmtransistor array are disposed on a lower display panel and the colorfilters are disposed on the thin film transistor array. In this case,the color filter may be used as a passivation layer that is providedbetween the thin film transistor array and pixel electrodes.Furthermore, the color filters may be disposed on the upper displaypanel 160. For explanatory convenience, exemplary embodiments of thepresent invention will be described below by using a liquid crystaldisplay having the AOC structure.

The lower display panel 150 is described in detail below.

Black matrices 90, which prevent light from leaking and define pixelregions, are disposed on a first insulating substrate 10 that may bemade of a transparent insulating material, such as glass. Each blackmatrix 90 may be made of a metal or a metal oxide, such as chromium orchromium oxide, or an organic black resist.

Red, green, and blue color filters 92 are sequentially arranged on thepixel region between the black matrices 90.

An overcoat layer 94, which planarizes the color filters 92 and theblack matrices 90, may be disposed on the color filters 92.

The gate line 22 is disposed on the overcoat layer 94 in a firstdirection, for example, in a horizontal direction. A gate electrode 26extends from the gate line 22. The gate line 22 and the gate electrode26 are referred to as gate wires.

A storage line (not shown) is disposed on the overcoat layer 94 in thehorizontal direction. The storage line (not shown) overlaps the pixelelectrode 82 to form a storage capacitor. The shape and arrangement ofthe storage line (not shown) may be modified in various ways. A commonvoltage Vcom may be applied to the storage line (not shown).

Each gate wire 22 and 26 and the storage line (not shown) may be made ofan aluminum-based metal, such as aluminum (Al) or an aluminum alloy, asilver-based metal, such as silver (Ag) or a silver alloy, acopper-based metal, such as copper (Cu) or a copper alloy, amolybdenum-based metal, such as molybdenum (Mo) or a molybdenum alloy,chromium (Cr), titanium (Ti), or tantalum (Ta). In addition, each gatewire 22 and 26 and the storage line (not shown) may have a multilayerstructure that includes two conductive films (not shown) havingdifferent physical properties. One of the two conductive films may bemade of a metal having low resistivity, for example, an aluminum-basedmetal, a silver-based metal, or a copper-based metal, to reduce signaldelay or voltage drop in each of the gate wires 22 and 26 and thestorage line (not shown). The other conductive film may be made of amaterial having excellent contact characteristics with respect to indiumtin oxide (ITO) and indium zinc oxide (IZO), for example, amolybdenum-based metal, chromium, titanium, or tantalum. A structurethat has a chromium lower film and an aluminum upper film, and astructure that has an aluminum lower film and a molybdenum upper filmmay be used as an example of the combination of the two conductivefilms. However, each gate wire 22 and 26 and the storage line (notshown) may be made of various metallic materials or conductors otherthan the above metallic materials.

A gate insulating film 30, which may be made of silicon nitride(SiN_(x)) or the like, is disposed on the gate wires 22 and 26 and thestorage line (not shown).

A semiconductor layer 40, which may be made of hydrogenated amorphoussilicon or polysilicon, is disposed on the gate insulating film 30. Thesemiconductor layer 40 may have various shapes, such as an island shapeor a stripe shape. For example, like in this exemplary embodiment, thesemiconductor layer 40 may be disposed on the gate electrode 26 and mayhave an island shape. Further, the semiconductor layer may be providedbelow the data line 62 and may extend to the upper portion of the gateelectrode 26 in a stripe shape. If the semiconductor layer has a stripeshape, the semiconductor layer may be formed by substantially the samepatterning process as the data line 62.

Ohmic contact layers 55 and 56 are disposed on the semiconductor layer40, and may be made of silicide or n+ hydrogenated amorphous silicon inwhich n-type impurities are doped at high concentration. Each ohmiccontact layer 55 and 56 may have any of various shapes, such as anisland shape or stripe shape. For example, when each ohmic contact layer55 and 56 has an island shape like in the present exemplary embodiment,the ohmic contact layers 55 and 56 may be provided below a drainelectrode 66 and a source electrode 65. When each ohmic contact layerhas a stripe shape, the ohmic contact layers 55 and 56 may extend to thelower portion of the data line 62.

The data line 62, the source electrode 65, and the drain electrode 66are disposed on the ohmic contact layers 55 and 56 and the gateinsulating layer 30. The data line 62 extends in a second direction, forexample, in a vertical direction, and crosses the gate line 22 to definea pixel. The source electrode 65 extends from the data line 62 to theupper portion of the semiconductor layer 40 in a branch shape. The drainelectrode 66 is spaced apart from the source electrode 65 and isprovided above the semiconductor layer 40 to face the source electrode65 with the gate electrode 26 therebetween. The thin film transistor isa three-terminal element that includes the gate electrode 26, the sourceelectrode 65, and the drain electrode 66. Further, the thin filmtransistor is a switching element that allows current to flow betweenthe source electrode 65 and the drain electrode 66 when a voltage isapplied to the gate electrode 26.

The drain electrode 66 includes a bar-shaped pattern, which is providedabove the semiconductor layer 40, and an extension portion. Theextension portion extends from the bar-shaped pattern to form a widearea, a portion of which is exposed by a contact hole 76.

The data line 62, the source electrode 65, and the drain electrode 66are referred to as data wires.

Each data wire 62, 65, and 66 may be a single film or a multilayer filmthat is made of one or more of aluminum, chromium, molybdenum, tantalum,and titanium. For example, each data wire 62, 65, and 66 may made of arefractory metal, such as chromium, molybdenum-based metal, tantalum, ortitanium. Further, each data wire 62, 65, and 66 may have a multilayerstructure in which an upper film (not shown) made of a low-resistancematerial is disposed on a lower film (not shown) made of a refractorymetal or the like. A three-layer structure that has a molybdenum film,an aluminum film, and a molybdenum film may be used as an example of themultilayer structure other than the above-mentioned dual-layerstructures that have a chromium lower film and an aluminum upper film,or the above mentioned dual-layer structure that has an aluminum lowerfilm and a molybdenum upper film.

At least a part of the source electrode 65 overlaps the semiconductorlayer 40. Further, the drain electrode 66 faces the source electrode 65with the gate electrode 26 therebetween, and at least a part of thedrain electrode 66 overlaps the semiconductor layer 40. In this case,the ohmic contact layers 55 and 56 are disposed between thesemiconductor layer 40 and the source electrode 65, and between thesemiconductor layer 40 and the drain electrode 66, respectively, toreduce the contact resistance therebetween.

A passivation layer 70, which may be made of an insulating film, isdisposed on the data wires 62, 65, and 66 and the semiconductor layer 40exposed through the data wires. In this case, the passivation layer 70may be made of an inorganic material such as silicon nitride or siliconoxide, an organic material that has a good planarizing characteristicsand photosensitivity, or an insulating material having a low dielectricconstant, such as a-Si:C:O or a-Si:O:F, that is formed by plasmaenhanced chemical vapor deposition (PECVD). In addition, the passivationlayer 70 may have a dual-layer structure, which includes a lowerinorganic layer and an upper organic layer, to improve characteristicsof the organic film and to protect the exposed semiconductor layer 40.In addition, red, green, and blue color filter layers may be used as thepassivation layer 70.

The contact hole 76, which exposes the drain electrode 66, is formed inthe passivation layer 70.

Micro-concave and convex portions are formed on the passivation layer 70by a mask that has patterns formed in a slit or lattice shape, or a maskhaving a translucent film.

The pixel electrode 82, which is connected to the drain electrode 66through the contact hole 76, is disposed on the passivation layer 70 tocorrespond to the shape of the pixel. The pixel electrode 82, to which adata voltage is applied, generates an electric field together with thecommon electrode 120 of the upper display panel 160, thereby determiningthe alignment of the liquid crystal molecules 175 that are providedbetween the pixel electrode 82 and the common electrode 120. In thiscase, the pixel electrode 82 may be made of a transparent electricconductor such as ITO or IZO, or a reflective electric conductor such asaluminum.

The pixel electrode 82 includes micro-concave and convex stripes 84 thatcorrespond to the micro-concave and convex portions disposed on thepassivation layer 70. Specifically, the pixel electrode 82 includes across-shaped connection portion 86 and the micro-concave and convexstripes 84. The cross-shaped connection portion 86 divides a pixelregion into four domain regions, and the micro-concave and convexstripes 84 are arranged in a specific direction in each domain. In thiscase, a domain is a region including a group of liquid crystal molecules175 that are inclined in a specific direction due to an electric fieldgenerated between the pixel electrode 82 and the common electrode 120.Further, the micro-concave and convex stripes 84 have a structure inwhich micro-concave portions 84 a and micro-convex portions 84 b arealternately arranged.

The micro-concave and convex stripes 84 are arranged in a diagonaldirection, and extend at an angle of about 45° or −45° with respect to apolarization axis of a polarizer (not shown) or the gate line 22. Whendriving power is applied to the liquid crystal display, the liquidcrystal molecules 175 are inclined in an extension direction of themicro-concave and convex stripes 84. Accordingly, the pixel region isdivided into four domain regions.

A capping layer (not shown) may further be disposed between thepassivation layer 70 and the pixel electrode 82. In this case, thecapping layer functions to separate the pixel electrode 82 from thepassivation layer 70. For example, silicon nitride (SiN_(x)) may be usedas a material of the capping layer.

An alignment film (not shown) to align the liquid crystal molecules 175may be disposed on the pixel electrode 82.

The upper display panel 160 facing the lower display panel 150 isdescribed in detail below.

A second insulating substrate 110, which may be made of a transparentinsulating material such as glass, is disposed to face the firstinsulating substrate 10. The common electrode 120, which may be made ofa transparent conductive material such as ITO or IZO, is disposed on thesecond insulating substrate 110. An alignment layer (not shown) to alignthe liquid crystal molecules 175 may be disposed on the common electrode120. Since a separate patterning process is not added for the commonelectrode 120, it may be possible to improve the transmittance of theliquid crystal display and to reduce the manufacturing costs.

The lower display panel 150 and the upper display panel 160 are alignedand combined with each other as described above and the liquid crystallayer 170 is disposed between the panels in the basic structure of theliquid crystal display according to the first exemplary embodiment ofthe present invention. The liquid crystal display is obtained bydisposing elements, such as polarizers and a backlight, on the basicstructure. In this case, the polarizers are disposed on both sides ofthe basic structure, respectively. The polarization axis of onepolarizer may be parallel to the gate line 22, and the polarization axisof the other polarizer may be orthogonal to the gate line.

When the electric field is not applied between the pixel electrodes 82and the common electrode 120, the liquid crystal molecules 175 includedin the liquid crystal layer 170 are aligned so that directors of theliquid crystal molecules are perpendicular to the lower display panel150 and the upper display panel 160. Further, the liquid crystalmolecules 175 may have negative dielectric anisotropy.

The movement of the liquid crystal molecules 175 of the liquid crystaldisplay according to the present exemplary embodiment of the inventionwill be described below with reference to FIG. 2 and FIG. 3.

Referring to FIG. 2, the pitch D1 of the micro-concave and convexstripes 84 should be as small as possible, for example, it may be 2.5times the cell gap G between the lower display panel 150 and the upperdisplay panel 160 or less, in order to effectively control the movementof the liquid crystal molecules 175. In this case, the pitch D1 of themicro-concave and convex stripes 84 is a gap between adjacentmicro-concave portions 84 a or a gap between adjacent micro-convexportions 84 b. For example, if the cell gap G is in the range of 3 μm to4 μm, the pitch D1 of the micro-concave and convex stripes 84 may be inthe range of 7.5 μm to 10 μm. In addition, if the pitch D1 is 2 μm ormore, it may be possible to obtain a horizontal electric field that cancontrol the movement of the liquid crystal molecules 175. Further, theheight difference D2 of the micro-concave and convex stripes 84, thatis, the difference in height between the micro-concave portion 84 a andthe micro-convex portion 84 b may be 0.5 to 1 times the pitch D1. If theheight difference D2 is larger than the pitch D1, the surface of thepixel electrode 82 would be excessively uneven. For this reason, it maybe difficult to obtain uniform characteristics of a display. If theheight difference D2 is smaller than 0.5 times the pitch D1, theintensity of the electric field generated by the micro-concave andconvex stripes 84 is small. For this reason, it may be difficult toaccurately control the movement direction of the liquid crystalmolecules 175.

When an electric field is not applied between the pixel electrode 82 andthe common electrode 120, the liquid crystal molecules 175 are alignedin the Z-direction.

If an electric field is applied between the pixel electrode 82 and thecommon electrode 120, a horizontal electric field and a verticalelectric field are generated between the pixel electrodes 82 and thecommon electrode 120 by the micro-concave and convex stripes 84.Accordingly, the liquid crystal molecules 175 are initially rotated inthe X-Z plane to be aligned parallel to the inclined surfaces of themicro-concave and convex stripes 84. Subsequently, the liquid crystalmolecules 175 are arranged in the extension direction of themicro-concave and convex stripes 84, that is, in the Y-direction due tothe interference with peripheral liquid crystal molecules 175, as shownin FIG. 3.

A method of manufacturing the liquid crystal display according to thefirst exemplary embodiment of the present invention will be described indetail below with reference to FIG. 4A, FIG. 4B, and FIG. 4C. FIG. 4A,FIG. 4B, and FIG. 4C are cross-sectional views showing processes of amethod of manufacturing the liquid crystal display according to thefirst exemplary embodiment of the present invention.

First, referring to FIG. 4A, the black matrix 90, the color filter 92,and the overcoat layer 94 are formed on the first insulating substrate10. Subsequently, the thin film transistor, which includes the gateelectrode 26, the drain electrode 66, the source electrode 65, thesemiconductor layer 40, and the ohmic contact layers 55 and 56, isformed. Then, the passivation layer 70 is formed on the thin filmtransistor.

Referring to FIG. 4B, light is radiated onto the passivation layer 70through a mask and then developed to form the contact hole 76, themicro-concave portions 84 a, and the micro-convex portions 84 b on thepassivation layer 70. In this case, the passivation layer 70 iscompletely removed from a region B corresponding to the contact hole 76so that the drain electrode 66 is exposed. Further, the passivationlayer 70 is partially removed from regions C corresponding to themicro-concave portions 84 a, so that the micro-concave portions 84 a andthe micro-convex portions 84 b are formed. The passivation layer 70remains in other regions A.

As described above, various methods may be used to make the thickness ofthe passivation layer 70 different in different regions. A mask that hasthe patterns formed in a slit or lattice shape, or a mask having atranslucent film is generally used to adjust the amount of lighttransmitting through the C regions.

In this case, the line width of the pattern between slits or a gapbetween the patterns, that is, the width of the slit should be smallerthan the resolution of an exposer used for exposure. When thetranslucent film is used, a thin film having a different transmittanceor a thin film having a different thickness may be used during themanufacture of the mask in order to adjust the transmittance.

Referring to FIG. 4C, the pixel electrode 82, which is connected to thedrain electrode 66 through the contact hole 76, is formed on thepassivation layer 70.

A capping layer (not shown) may further be formed between thepassivation layer 70 and the pixel electrode 82. In this case, thecapping layer functions to separate the pixel electrode 82 from thepassivation layer 70. The capping layer may be formed after thepassivation layer 70 is patterned. Alternatively, the capping layer andthe passivation layer 70 may be patterned simultaneously.

Subsequently, the lower display panel 150 and the upper display panel160 are aligned and combined with each other as shown in FIG. 2 and theliquid crystal layer 170 is disposed between the panels to complete theliquid crystal display.

A liquid crystal display according to a second exemplary embodiment ofthe present invention will be described below with reference to FIG. 5Aand FIG. 5B. FIG. 5A is a layout of a liquid crystal display accordingto a second exemplary embodiment of the present invention. FIG. 5B is across-sectional view of the liquid crystal display taken along lineVb-Vb′ of FIG. 5A. For explanatory convenience, components having thesame functions as those shown in the drawings (FIG. 1, FIG. 2, FIG. 3,FIG. 4A, FIG. 4B, and FIG. 4C) of the first exemplary embodiment will beindicated by the same reference numerals, and the description thereofwill be omitted. The difference between the first and second exemplaryembodiments will be described below.

A pixel electrode 82 includes a cross-shaped connection portion 286 andmicro-concave and convex stripes 84. The cross-shaped connection portion286 divides a pixel region into four domain regions, and themicro-concave and convex stripes 84 are arranged in a specific directionin each domain. In this case, the connection portion 286 protrudestoward a common electrode 120, so that a horizontal electric field maybe generated. As described above, liquid crystal molecules 175 areinclined in an extension direction of the micro-concave and convexstripes 84 due to the micro-concave and convex stripes 84. A horizontalelectric field generated by the connection portion 286 determines thealignment of the liquid crystal molecules 175, that is, determineswhether the liquid crystal molecules 175 are inclined toward one side ofthe micro-concave and convex stripes 84 or the other side of themicro-concave and convex stripes 84.

The width W1 of the connection portion 286 should be 2.5 times the cellgap or more to effectively control the inclination direction of theliquid crystal molecules by the horizontal electric field generated bythe connection portion 286.

A liquid crystal display according to a third exemplary embodiment ofthe present invention will be described below with reference to FIG. 6Aand FIG. 6B. FIG. 6A is a layout of a liquid crystal display accordingto a third exemplary embodiment of the present invention. FIG. 6B is across-sectional view of the liquid crystal display taken along lineVIb-VIb′ of FIG. 6A. For explanatory convenience, components having thesame functions as those shown in the drawings (FIG. 5A and FIG. 5B) ofthe second exemplary embodiment will be indicated by the same referencenumerals, and the description thereof will be omitted. The differencebetween the second and third exemplary embodiments will be mainlydescribed below.

A pixel electrode 82 includes a cross-shaped cut-out portion 288 andmicro-concave and convex stripes 84. The cross-shaped cut-out portion288 divides a pixel region into four domain regions, and themicro-concave and convex stripes 84 are arranged in a specific directionin each domain. In this case, the cut-out portion 288 is formed bypartially removing a part of the pixel electrode from the pixelelectrode 82, and generates a horizontal electric field. As describedabove, liquid crystal molecules 175 are inclined in an extensiondirection of the micro-concave and convex stripes 84 due to themicro-concave and convex stripes 84. A horizontal electric fieldgenerated by the cut-out portion 288 determines the inclinationdirection of the liquid crystal molecules 175, that is, determineswhether the liquid crystal molecules 175 are inclined toward one side ofthe micro-concave and convex stripes 84 or the other side of themicro-concave and convex stripes 84.

The width W2 of the cut-out portion 288 should be 2.5 times the cell gapor more in order to effectively control the inclination direction of theliquid crystal molecules 175 by the horizontal electric field generatedby the cut-out portion 288.

A liquid crystal display according to a fourth exemplary embodiment ofthe present invention will be described below with reference to FIG. 7,FIG. 8, FIG. 9, FIG. 10, and FIG. 1. FIG. 7 is a layout of a lowerdisplay panel that includes in a liquid crystal display according to afourth exemplary embodiment of the present invention. FIG. 8 is across-sectional view of the lower display panel taken along lineVIII-VIII′ of FIG. 7. FIG. 9 is a cross-sectional view of the lowerdisplay panel taken along line IX-IX′ of FIG. 7. FIG. 10 is a layout ofan upper display panel included in the liquid crystal display accordingto the fourth exemplary embodiment of the present invention. FIG. 11 isa layout of the liquid crystal display that includes the lower displaypanel of FIG. 7 and the upper display panel of FIG. 10.

A liquid crystal display according to a fourth exemplary embodiment ofthe present invention includes a lower display panel, an upper displaypanel, and a liquid crystal layer. The lower display panel includes thinfilm transistors that are connected to gate lines 322 and data lines 362and apply data voltages to pixel electrodes 382. The upper display panelfaces the lower display panel and includes a common electrode 490. Theliquid crystal layer is disposed between the lower display panel and theupper display panel.

The lower display panel will be described in detail below with referenceto FIG. 7, FIG. 8, and FIG. 9.

A gate line 322 and a gate electrode 326 are disposed on a firstinsulating substrate 310, and a gate insulating layer 330 is disposed onthe gate line 322 and the gate electrode 326. A semiconductor layer 340and ohmic contact layers 355 and 356 are disposed on the gate insulatinglayer 330. A data line 362, a source electrode 365, and a drainelectrode 366 are disposed on the ohmic contact layers 355 and 356 andthe gate insulating layer 330. A passivation layer 370 is disposed onthe data line 362, the source electrode 365, and the drain electrode366, and the semiconductor layer 340 that is exposed between the sourceelectrode 365 and the drain electrode 366. A contact hole 376 throughwhich the drain electrode 366 is exposed is formed in the passivationlayer 370.

The gate line 322, the gate electrode 326, the gate insulating layer330, the semiconductor layer 340, the ohmic contact layers 355 and 356,the data line 362, the source electrode 365, the drain electrode 366,the passivation layer 370, and the contact hole 376 of this exemplaryembodiment may be substantially the same as the gate lines 22, the gateelectrode 26, the gate insulating layer 30, the semiconductor layer 40,the ohmic contact layers 55 and 56, the data line 62, the sourceelectrode 65, the drain electrode 66, the passivation layer 70, and thecontact hole 76 that are shown in FIG. 1, respectively, in terms ofshape and materials thereof.

Micro-concave and convex portions 384 are formed on the regions of thepassivation layer 370 that correspond to the edges of the pixelelectrode 382.

The pixel electrode 382, which is connected to the drain electrode 366through the contact hole 376 and positioned on a pixel region, isdisposed on the passivation layer 370. In this case, the pixel electrode82 may be made of a transparent electric conductor such as ITO or IZO,or a reflective electric conductor such as aluminum. The pixel electrode382 may have a V shape.

Micro-concave and convex stripes 384 are conformally formed at the edgesof the pixel electrode 382 to correspond to the micro-concave and convexportions formed on the passivation layer 370.

The pixel electrode 382 has a bent structure that has at least one bentportion. For example, the pixel electrode 382 of this exemplaryembodiment has one bent portion, but the present invention is notlimited by the number of the bent portions. The pixel electrode 382 isbent at an angle of about 45° or −45° with respect to a polarizationaxis of a polarizer or the gate line 322.

The micro-concave and convex stripes 384 function to reinforce thehorizontal electric field, thereby facilitating the inclination of theliquid crystal molecules of the liquid crystal layer. The micro-concaveand convex stripes 384 have a structure in which micro-concave portions384 a and micro-convex portions 384 b are alternately arranged. Themicro-concave and convex stripes 384 are arranged in a diagonaldirection, and extend at an angle of about 45° or −45° with respect to apolarization axis of a polarizer (not shown) or the gate line 322. Themicro-concave and convex stripes 384 may extend in a directionsubstantially orthogonal to the edges of the pixel electrode 382. Whendriving power is applied to the liquid crystal display, the liquidcrystal molecules are inclined in an extension direction of themicro-concave and convex stripes 384. Accordingly, the pixel region isdivided into four domain regions.

The micro-concave and convex stripes 384 of this exemplary embodimentmay be substantially the same as the micro-concave and convex portionsstripes 84 shown in FIG. 1 in terms of structure and functions thereof.That is, the pitch of the micro-concave and convex stripes 384 should beas small as possible and for example, may be 2.5 times the cell gapbetween the lower display panel and the upper display panel or less, inorder to effectively control the movement of the liquid crystalmolecules. In addition, if the pitch is 2 μm or more, it may be possibleto obtain a horizontal electric field sufficient to control the movementof the liquid crystal molecules. Further, the height difference of themicro-concave and convex stripes 384, that is, the difference in heightbetween the micro-concave portions 384 a and the micro-convex portions384 b, should be 0.5 to 1 times the pitch.

A capping layer (not shown) may further be disposed between thepassivation layer 370 and the pixel electrode 382. In this case, thecapping layer functions to separate the pixel electrode 382 from thepassivation layer 370. For example, SiN_(x) may be used as a material ofthe capping layer.

The upper display panel facing the lower display panel will be describedin detail below with reference to FIG. 10 and FIG. 11.

Black matrices 491, which prevent light from leaking and define pixelregions, are disposed on a second insulating substrate (not shown),which may be made of a transparent insulating material such as glass.Red, green, and blue color filters (not shown) are sequentially arrangedon the pixel region between the black matrices 491. An overcoat layer(not shown) may be disposed on the substrate to planarize the blackmatrices 491 and color. The common electrode 490, which may be made of atransparent conductive material such as ITO or IZO, is disposed on theovercoat layer.

In this case, the common electrode 490 includes a domain-dividingportion 492. The domain-dividing portion faces the pixel electrodes 382and is inclined at an angle of about 45° or −45° with respect to apolarization axis of a polarizer or the gate line 322. Thedomain-dividing portion 492 has a bent shape corresponding to the bentshape of the pixel. That is, the domain-dividing portion 492 has a Vshape. The domain-dividing portion 492 may be a cut-out portion of thecommon electrode 490 or a protrusion formed on the common electrode 490.After one pixel is divided into a plurality of domains by thedomain-dividing portion 492, the domain-dividing portion 492 maydetermine the inclination direction of the liquid crystal molecules.Accordingly, the inclination direction of the liquid crystal moleculesis diversified by the domain-dividing portion 492, so that it may bepossible to increase a reference viewing angle.

In this way, the pixel is divided into a plurality of domains by thedomain-dividing portion 492 of the common electrode 490 and the edges ofthe pixel electrode 382. In this case, the domain of the pixel isdivided into left and right pieces by the domain-dividing portion 492,and divided into upper and lower pieces by the bent portion of the pixelelectrode 382. That is, the pixel is divided into four domains dependingon a direction where main directors of the liquid crystal moleculesincluded in the liquid crystal layer are arranged due to an electricfield.

The domain-dividing portion 492 may include notches (not shown) thathave the shape of a recessed chamfer. The notches may have a triangular,a rectangular, a trapezoid, or a semicircular shape. The liquid crystalmolecules arranged at domain boundaries may be stably and regularlyarranged by the notches. Therefore, it may be possible to preventdisplay irregularities or residual images from occurring at the domainboundaries.

An alignment layer (not shown) to align the liquid crystal molecules maybe disposed on the common electrode 490.

The lower display panel and the upper display panel are aligned andcombined with each other as described above and the liquid crystal layeris disposed between the panels to complete the basic structure of theliquid crystal display according to the first exemplary embodiment ofthe present invention. The liquid crystal display is obtained bydisposing elements, such as polarizers and a backlight, on the basicstructure. In this case, the polarizers are disposed on both sides ofthe basic structure, respectively. The polarization axis of onepolarizer may be parallel to the gate line 322, and the polarizationaxis of the other polarizer may be orthogonal to the gate line 322.

When the electric field is not applied between the pixel electrodes 382and the common electrode 490, the liquid crystal molecules are alignedso that directors of the liquid crystal molecules are perpendicular tothe lower display panel and the upper display panel. Further, the liquidcrystal molecules may have negative dielectric anisotropy.

A liquid crystal display according to a fifth exemplary embodiment ofthe present invention will be described below with reference to FIG. 12and FIG. 13. FIG. 12 is a layout of a liquid crystal display accordingto a fifth exemplary embodiment of the present invention. FIG. 13 is across-sectional view of the liquid crystal display taken along lineXIII-XIII′ of FIG. 12.

Referring to FIG. 12 and FIG. 13, the liquid crystal display accordingto the fifth exemplary embodiment of the present invention includes alower display panel, an upper display panel, and a liquid crystal layer.The lower display panel includes thin film transistors that areconnected to gate lines 422, first data lines 462 a, and second datalines 462 b and apply data voltages to pixel electrodes 482 a. The upperdisplay panel faces the lower display panel and includes a commonelectrode 120. The liquid crystal layer is interposed between the lowerdisplay panel and the upper display panel. According to the presentexemplary embodiment, color filters 92 and a thin film transistor arrayare disposed in the lower display panel, and the present exemplaryembodiment will be described by using AOC structure where the thin filmtransistor array is disposed on the color filters 92. However, thepresent invention is not limited thereto. That is, exemplary embodimentsof the present invention also may employ COA structure a thin filmtransistor array are disposed on a lower display panel and the colorfilters are disposed on the thin film transistor array. In this case,the color filter may be used as a passivation layer that is providedbetween the thin film transistor array and pixel electrodes.Furthermore, the color filters may be disposed on the upper displaypanel. For explanatory convenience, exemplary embodiments of the presentinvention will be described below using a liquid crystal display havingthe AOC structure.

The lower display panel is described in detail below.

Black matrices 90 are disposed on a first insulating substrate 10, whichmay be made of a transparent insulating material such as glass. Red,green, and blue color filters 92 are sequentially arranged on the pixelregion between the black matrices 90. An overcoat layer 94 may bedisposed on the substrate to planarize the black matrices 90 and thecolor filters 92.

The gate line 422 through which a gate signal is transmitted is disposedon the overcoat layer 94 in a first direction, for example, in ahorizontal direction. A pair of (first and second) gate electrodes 426 aand 426 b extends from the gate line 22. The gate line 422 and the firstand second gate electrodes 426 a and 426 b are referred to as gatewires.

Further, control electrodes 482 b, which divide the pixel region into aplurality of domains, are disposed on the overcoat layer 94. The controlelectrode 482 b is positioned at the central portion of the pixelelectrode 482 a and has a bent shape, for example, a V-shape. Althoughshown in FIG. 13 as being formed on the same layer as the gate wires,the control electrode 482 b may alternatively be disposed on the samelayer as the pixel electrode 482 a or the data lines 462 a and 462 b,and may be made of the same material as the pixel electrode 482 a or thedata lines 462 a and 462 b.

A storage line (not shown), which crosses the pixel region and extendsin the horizontal direction so as to be substantially parallel to thegate line 422, may be disposed on the overcoat layer 94. The storageline overlaps the pixel electrode 482 a, thereby forming a storagecapacitor that may store charge.

Each gate wire 422, 426 a, and 426 b and the control electrodes 482 bmay be made of an aluminum-based metal, such as aluminum (Al) or analuminum alloy, a silver-based metal, such as silver (Ag) or a silveralloy, a copper-based metal, such as copper (Cu) or a copper alloy, amolybdenum-based metal, such as molybdenum (Mo) or a molybdenum alloy,chromium (Cr), titanium (Ti), or tantalum (Ta). In addition, each gatewires 422, 426 a, and 426 b and the control electrodes 482 b may have amultilayer structure that includes two conductive films (not shown)having different physical properties. One conductive film of the twoconductive films may be made of a metal having low resistivity, forexample, an aluminum-based metal, a silver-based metal, or acopper-based metal, to reduce signal delay or voltage drop in each gatewire 422, 426 a, and 426 b and the control electrode 482 b. The otherconductive film may be made of a material having excellent contactcharacteristics with respect to ITO and IZO, for example, amolybdenum-based metal, chromium, titanium, or tantalum. A structurethat has a chromium lower film and an aluminum upper film, and astructure that has an aluminum lower film and a molybdenum upper filmmay be used as an example of the combination of the two conductivefilms. However, each gate wire 422, 426 a, and 426 b and the controlelectrodes 482 b may be made of various metallic materials or conductorsother than the above metallic materials.

A gate insulating layer 430 made of silicon nitride (SiN_(x)) isdisposed on the gate wires 422, 426 a, and 426 b, and the controlelectrode 482 b.

A pair of (first and second) semiconductor layers 440 a and 440 b, whichmay be made of hydrogenated amorphous silicon or polysilicon, isdisposed on the gate insulating film 430. The first and secondsemiconductor layers 440 a and 440 b may have various shapes, such as anisland shape and a stripe shape. For example, like in this exemplaryembodiment, the semiconductor layers 440 a and 440 b may each have anisland shape.

Ohmic contact layers 455 a, 455 b, 456 a, and 456 b are disposed on eachsemiconductor layer 440 a and 440 b, and may be made of silicide orn+hydrogenated amorphous silicon in which n-type impurities are doped athigh concentration. The ohmic contact layers 455 a, 455 b, 456 a, and456 b are positioned in pairs on the semiconductor layers 440 a and 440b.

A pair of (first and second) data lines 462 a and 462 b and a pair of(first and second) drain electrodes 466 a and 466 b are disposed on theohmic contact layers 455 a, 455 b, 456 a, and 456 b and the gateinsulating layer 430. The drain electrodes 466 a and 466 b correspond tothe first and second data lines 462 a and 462 b, respectively.

The first and second data lines 462 a and 462 b extend in a verticaldirection to cross the gate line 422. The first and second data lines462 a and 462 b transmit a data voltage and a control voltage. The firstand second data lines 462 a and 462 b are provided with first and secondsource electrodes 465 a and 465 b that extend toward the first andsecond drain electrodes 466 a and 466 b, respectively. As shown in FIG.12, the first data line 462 a transmits a data signal to the pixelelectrode 482 a, and the second data line 462 b transmits a controlsignal to the control electrode 482 b.

A contact hole 476 b is formed in the gate insulating layer 430. Thesecond drain electrode 466 b is connected to the control electrode 482 bthrough the contact hole 476 b, so that a control voltage may be appliedto the control electrode 482 b.

The first and second data lines 462 a and 462 b, the first and secondsource electrodes 465 a and 465 b, and the first and second drainelectrodes 466 a and 466 b are referred to as data wires.

Each data wire 462 a, 462 b, 465 a, 465 b, 466 a, and 466 b may be madeof a refractory metal, such as chromium, molybdenum-based metal,tantalum, or titanium. Further, each data wire 462 a, 462 b, 465 a, 465b, 466 a, and 466 b may have a multilayer structure in which an upperfilm (not shown), which may be made of a low-resistance material, isformed on a lower film (not shown), which may be made of a refractorymetal or the like. A three-layer structure that has a molybdenum film,an aluminum film, and a molybdenum film may be used as an example of themultilayer structure other than the above-mentioned dual-layerstructures that have a chromium lower film and an aluminum upper film,or the above mentioned dual-layer structure that has an aluminum lowerfilm and a molybdenum upper film.

At least a part of the first and second source electrodes 465 a and 465b overlap the semiconductor layers 440 a and 440 b, respectively.Further, the first and second drain electrodes 466 a and 466 b face thefirst and second source electrodes 465 a and 465 b with the gateelectrodes 426 a and 426 b therebetween, and at least a part of thedrain electrodes overlap the semiconductor layers 440 a and 440 b,respectively. In this case, the above-mentioned ohmic contact layers 455a, 455 b, 456 a, and 456 b are disposed between the semiconductor layers440 a and 440 b and the first and second source electrodes 465 a and 465b, and between the semiconductor layers 440 a and 440 b and the firstand second drain electrodes 466 a and 466 b, respectively, to reduce thecontact resistance therebetween.

A passivation layer 470 is disposed on the data wires 462 a, 462 b, 465a, 465 b, 466 a, and 466 b and the semiconductor layers 440 a and 440 bexposed through the data wires. In this case, the passivation layer 470,which may be made of an inorganic material such as silicon nitride orsilicon oxide, an organic material that has a good planarizingcharacteristic and photosensitivity, or an insulating material having alow dielectric constant such as a-Si:C:O or a-Si:O:F that is formed byplasma enhanced chemical vapor deposition (PECVD). In addition, thepassivation layer 470 may have a dual-layer structure, which includes alower inorganic layer and an upper organic layer, to improvecharacteristics of the organic film and to protect the exposedsemiconductor layers 440 a and 440 b. In addition, red, green, and bluecolor filter layers may be used as the passivation layer 470.

A contact hole 476 a is formed in the passivation layer 470, andmicro-concave and convex portions are formed on regions of thepassivation layer 470 that correspond to the edges of the pixelelectrode 482 a.

The pixel electrode 482 a disposed on the passivation layer 470 isconnected to the first drain electrode 466 a through the contact hole476 a, so that a data voltage may be applied to the pixel electrode 482a. The micro-concave and convex stripes 384, which are conformallyformed to correspond to the micro-concave and convex portions formed onthe passivation layer 470, are arranged at the edges of the pixelelectrode 482 a. In this case, the micro-concave and convex stripes 384function to reinforce the horizontal electric field, therebyfacilitating the inclination of the liquid crystal molecules of theliquid crystal layer. The micro-concave and convex stripes 384 have astructure where micro-concave portions 384 a and micro-convex portions384 b are alternately arranged. The micro-concave and convex stripes 384are arranged in a diagonal direction and extend at an angle of about 45°or −45° with respect to a polarization axis of a polarizer (not shown)or the gate line 422. The micro-concave and convex stripes 384 mayextend in a direction substantially orthogonal to the edges of the pixelelectrode 482 a. When driving power is applied to the liquid crystaldisplay, the liquid crystal molecules are inclined in an extensiondirection of the micro-concave and convex stripes 384. Accordingly, thepixel region is divided into four domain regions.

The pixel electrode 482 a, to which a data voltage is applied, generatesan electric field together with the common electrode 120 of the upperdisplay panel, thereby determining the arrangement of the liquid crystalmolecules that are provided between the pixel electrode 482 a and thecommon electrode 120. The pixel electrode 482 a may be made of atransparent electric conductor such as ITO or IZO, or a reflectiveelectric conductor such as aluminum.

The pixel electrode 482 includes a cut-out portion 486 that is inclinedat an angle of about 45° or −45° with respect to the gate line 422 or apolarization axis of a polarizer. The cut-out portion 486 may have abent shape corresponding to the bent shape of the pixel. That is, thecut-out portion 486 may be V-shaped.

The control electrode 482 b is disposed to overlap with the cut-outportion 486. The control electrode 482 b may be narrower than thecut-out portion 486, and the control electrode 482 b may be disposed inthe cut-out portion 486.

A control voltage applied to the control electrode 482 b should beslightly higher than a data voltage applied to the pixel electrode 482a. In this case, the level of the voltage means the magnitude of thevoltage relative to the common voltage. If a control voltage higher thana data voltage is applied to the control electrode 482 b, anequipotential line of the liquid crystal layer is convex toward thecommon electrode 120 in the vicinity of the control electrode 482 b.Accordingly, the liquid crystal molecules are inclined in a directionperpendicular to the direction of the electric field. For this reason,the liquid crystal molecules provided on both sides of the controlelectrode 482 b are inclined toward the control electrode 482 b.Therefore, the domain of the pixel region is divided by the controlelectrode 482 b.

An alignment film (not shown) to align the liquid crystal layer may bedisposed on the pixel electrode 482 a and the passivation layer 470.

The upper display panel facing the lower display panel is described indetail below.

A second insulating substrate 110, which may be made of a transparentinsulating material such as glass, is disposed to face the firstinsulating substrate 10. The common electrode 120, which may be made ofa transparent conductive material such as ITO or IZO, is disposed on thesecond insulating substrate 110. An alignment layer (not shown) to alignthe liquid crystal layer 170 may be disposed on the common electrode120. Since a separate patterning process is not added for the commonelectrode 120, it may be possible to improve the transmittance of theliquid crystal display and to reduce the manufacturing costs.

The lower display panel and the upper display panel are aligned andcombined with each other as described above and the liquid crystal layer170 is disposed between the panels to complete the basic structure ofthe liquid crystal display according to the fifth exemplary embodimentof the present invention. The liquid crystal display is obtained bydisposing elements, such as polarizers and a backlight, on the basicstructure. In this case, the polarizers are disposed on both sides ofthe basic structure, respectively. The polarization axis of onepolarizer may be parallel to the gate line 422, and the polarizationaxis of the other polarizer may be orthogonal to the gate line 422.

When the electric field is not applied between the pixel electrodes 482a and the common electrode 120, the liquid crystal molecules included inthe liquid crystal layer 170 are aligned so that directors of the liquidcrystal molecules are perpendicular to the lower display panel and theupper display panel. Further, the liquid crystal molecules may havenegative dielectric anisotropy.

In the liquid crystal display according to the exemplary embodiment ofthe present invention, micro-concave and convex stripes are formed on apixel electrode as described above. Therefore, it may be possible toeffectively control the movement of the liquid crystal molecules. As aresult, it may be possible to improve the response speed and luminanceof the liquid crystal display.

It will be apparent to those skilled in the art that variousmodifications and variation can be made in the present invention withoutdeparting from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A liquid crystal display, comprising: a first insulating substrate;pixel electrodes disposed on the first insulating substrate and dividedinto a plurality of domains, each domain comprising micro-concavestripes and micro-convex stripes arranged in a specific direction; asecond insulating substrate facing the first insulating substrate; acommon electrode, which is not patterned, disposed on the secondinsulating substrate; and a liquid crystal layer disposed between thefirst insulating substrate and the second insulating substrate, theliquid crystal layer comprising liquid crystal molecules, the liquidcrystal molecules being aligned perpendicular to the first insulatingsubstrate and the second insulating substrates when an electric field isnot applied to the liquid crystal layer, wherein the liquid crystalmolecules are inclined in an extension direction of the micro-concaveand convex stripes when an electric field is applied to the liquidcrystal layer.
 2. The liquid crystal display of claim 1, wherein thepitch of the micro-concave stripes and the micro-convex stripes is notgreater than 2.5 times a cell gap between the first insulating substrateand the second insulating substrate.
 3. The liquid crystal display ofclaim 2, wherein a difference in height between the micro-concavestripes and the micro-convex stripes is 0.5 to 1 times the pitch.
 4. Theliquid crystal display of claim 1, further comprising: a first polarizerdisposed on the first insulating substrate; and a second polarizerdisposed on the second insulating substrate, wherein the micro-concavestripes and the micro-convex stripes extend at an angle of 45° or −45°with respect to a polarization axis of the polarizers.
 5. The liquidcrystal display of claim 1, further comprising: a capping layer disposedbetween the first insulating substrate and the pixel electrodes, thecapping layer contacting the pixel electrodes.
 6. The liquid crystaldisplay of claim 1, wherein each pixel electrode further comprises aconnection portion that divides the pixel electrode into a plurality ofdomains, and the connection portion protrudes toward the commonelectrode.
 7. The liquid crystal display of claim 6, wherein a width ofthe connection portion is at least 2.5 times a cell gap between thefirst insulating substrate and the second insulating substrate.
 8. Theliquid crystal display of claim 1, wherein each pixel electrode furthercomprises a cut-out portion that divides the pixel electrode into theplurality of domains.
 9. The liquid crystal display of claim 8, whereina width of the cut-out portion is at least 2.5 times a cell gap betweenthe first insulating substrate and the second insulating substrate. 10.A liquid crystal display, comprising: a first insulating substrate;pixel electrodes disposed on the first insulating substrate, having abent structure, and comprising micro-concave stripes and micro-convexstripes that extend along edges of the pixel electrode to be orthogonalto the edges of the pixel electrode; a second insulating substratefacing the first insulating substrate; a common electrode disposed onthe second insulating substrate and comprising a domain-dividingportion; and a liquid crystal layer disposed between the firstinsulating substrate and the second insulating substrate and comprisingliquid crystal molecules, the liquid crystal molecules being alignedperpendicular to the first insulating substrate and the secondinsulating substrate when an electric field is not applied to the liquidcrystal layer, wherein the liquid crystal molecules are inclined in anextension direction of the micro-concave stripes and the micro-convexstripes when an electric field is applied to the liquid crystal layer.11. The liquid crystal display of claim 10 wherein a pitch of themicro-concave stripes and the micro-convex stripes is not greater than2.5 times a cell gap between the first insulating substrate and thesecond insulating substrate.
 12. The liquid crystal display of claim 11,wherein a difference in height between the micro-concave stripes and themicro-convex stripes is 0.5 to 1 times the pitch.
 13. The liquid crystaldisplay of claim 10, further comprising: a first polarizer disposed onthe first insulating substrate; and a second polarizer disposed on thesecond insulating substrate, wherein the micro-concave stripes and themicro-convex stripes extend at an angle of 45° or −45° with respect to apolarization axis of the polarizers.
 14. The liquid crystal display ofclaim 10, further comprising: a capping layer disposed between the firstinsulating substrate and the pixel electrodes, the capping layercontacting the pixel electrodes.
 15. A liquid crystal display,comprising: a first insulating substrate; pixel electrodes disposed onthe first insulating substrate, having a bent structure, and comprisingmicro-concave stripes and micro-convex stripes that extend along edgesof the pixel electrode to be orthogonal to the edges of the pixelelectrode; control electrodes overlapping with cut-out portions in thepixel electrodes, the control electrodes receiving a voltage higher thanthat applied to the pixel electrodes; a second insulating substratefacing the first insulating substrate; a common electrode, which is notpatterned, disposed on the second insulating substrate; and a liquidcrystal layer disposed between the first insulating substrate and thesecond insulating substrate, the liquid crystal layer comprising liquidcrystal molecules, the liquid crystal molecules being alignedperpendicular to the first insulating substrate and the secondinsulating substrate when an electric field is not applied to the liquidcrystal layer, wherein the liquid crystal molecules are inclined in anextension direction of the micro-concave stripes and the micro-convexstripes when an electric field is applied to the liquid crystal layer.16. The liquid crystal display of claim 15, wherein a pitch of themicro-concave stripes and the micro-convex stripes is not greater than2.5 times a cell gap between the first insulating substrate and thesecond insulating substrate.
 17. The liquid crystal display of claim 16,wherein a difference in height between the micro-concave stripes and themicro-convex stripes is 0.5 to 1 times the pitch.
 18. The liquid crystaldisplay of claim 15, further comprising: a first polarizer disposed onthe first insulating substrate; and a second polarizer disposed on thesecond insulating substrate, wherein the micro-concave stripes and themicro-convex stripes extend at an angle of 45° or −45° with respect to apolarization axis of the polarizers.
 19. The liquid crystal display ofclaim 15, further comprising: a capping layer disposed between the firstinsulating substrate and the pixel electrodes, the capping layercontacting the pixel electrodes.
 20. The liquid crystal display of claim15, further comprising: gate lines disposed on the first insulatingsubstrate; and first data lines and second data lines crossing the gatelines, wherein data voltages are applied to the pixel electrodes fromthe first data lines, and control voltages are applied to the controlelectrodes from the second data lines.